Exposure apparatus and method for manufacturing device

ABSTRACT

An exposure apparatus wherein an image of a pattern is projected onto a substrate via a projection optical system to expose the substrate, includes: a substrate moving device that is movable while holding the substrate above the projection optical system; and a liquid immersion unit that fills at least a portion of the space between the projection optical system and the substrate with a liquid, wherein the image of the pattern is projected onto the substrate via the projection optical system and the liquid.

CROSS-REFERENCE TO RELATED APPLICATION

This is a Continuation of application Ser. No. 11/257,089 filed Oct. 25,2005, which is a Divisional of application Ser. No. 11/239,402 filedSep. 30, 2005, which is a Continuation of International Application No.PCT/JP2004/004969 filed Apr. 6, 2004, which claims priority to JapanesePatent Application No. 2003-103145, filed Apr. 7, 2003. The content ofeach of the aforementioned applications is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exposure apparatus and a devicemanufacturing method in which an image of a pattern isprojection-exposed onto a substrate via a projection optical system and,in particular, to a liquid immersion type exposure apparatus.

2. Description of Related Art

Semiconductor devices and liquid crystal display devices aremanufactured through the so-called photolithography technique, by whicha pattern formed on a mask is transferred onto a photosensitivesubstrate. The exposure apparatus used in the photolithography processhas a mask stage that supports a mask and a substrate stage thatsupports a substrate, and transfers the mask pattern, via a projectionoptical system, onto the substrate while successively moving the maskstage and the substrate stage. In recent years, there has been demandfor higher resolution projection optical systems in order to handle themuch higher levels of integration of device patterns. As the exposurewavelength to be used is shorter, the resolution of the projectionoptical system becomes higher. As the numerical aperture of theprojection optical system is larger, the resolution of the projectionoptical system becomes higher. Consequently, the exposure wavelengthused in exposure apparatuses has shortened year by year, and thenumerical aperture of projection optical systems has also increased.Furthermore, the currently mainstream exposure wavelength is the 248 nmKrF excimer laser, but an even shorter wavelength 193 nm ArF excimerlaser is also being commercialized. In addition, as well as resolution,the depth of focus (DOF) is also important when performing an exposure.The resolution R and the depth of focus δ are respectively expressed bythe following formulas:R=k ₁ ·λ/NA,  (1)δ=±k ₂ ·λ/NA ²,  (2)where λ is the exposure wavelength, NA is the numerical aperture of theprojection optical system, and k₁ and k₂ are process coefficients. Itcan be seen from formulas (1) and (2) that if, to enhance the resolutionR, the wavelength λ is made shorter and the numerical aperture is madelarger, then the depth of focus δ becomes narrower.

When the depth of focus δ becomes too narrow, it becomes difficult tomake the substrate surface coincide with the image plane of theprojection optical system, and thus there occurs the possibility thatthe focus margin during the exposure operation will be insufficient.Accordingly, the liquid immersion method has been proposed, as disclosedin, for example, Japanese Unexamined Patent Application, FirstPublication No. H10-303114, as a method to substantially shorten theexposure wavelength and increase the depth of focus. This liquidimmersion method is designed to, by filling the space between the undersurface of the projection optical system and the substrate surface witha liquid, e.g., water or organic solvent, form a liquid immersion regionand thus by taking advantage of the fact that the wavelength of theexposure light in the liquid becomes 1/n times (n is the refractiveindex of the liquid and is generally about 1.2 to 1.6) of that in theair, improve the resolution and, at the same time, enlarge the depth offocus by approximately n times.

By the way, with the above-mentioned related art, there are problems asdescribed below.

The immersion liquid type exposure apparatus disclosed in theabove-mentioned Japanese Unexamined Patent Application, FirstPublication No. H10-303114, is configured such that a liquid bath isformed of a holder table, wall portions, etc. on a substrate stage, anda substrate is positioned in the liquid bath. In the case of such aconfiguration, when the substrate stage is moved, there arises not onlythe possibility that the liquid surface undulates and the liquidscatters, but also the possibility that the pattern image projected ontothe substrate deteriorates due to the undulation of the liquid. Inaddition, pipings for supplying and recovering the liquid need to beconnected to the substrate stage, which may adversely affect themovement accuracy of the stage.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of such situations,and its objective is to provide an exposure apparatus and a devicemanufacturing method in which scattering of the liquid for forming aliquid immersion region is suppressed, the movement of the substratestage is not obstructed by pipings and the like for supplying andrecovering the liquid, and a substrate can be exposed with a requiredpattern accuracy.

To resolve the above-described problems, the present invention adoptsthe following configuration corresponding to FIGS. 1 to 8 as illustratedin embodiments.

An exposure apparatus of the present invention is an exposure apparatuswherein an image of a pattern is projected onto a substrate via aprojection optical system to expose the substrate, the exposureapparatus includes a substrate moving means that is movable whileholding the substrate above the projection optical system and a liquidimmersion unit that fills at least a portion of the space between theprojection optical system, wherein the substrate with a liquid andprojects the image of a pattern onto the substrate via the projectionoptical system and the liquid.

Further, a device manufacturing method of the present invention uses theabove-described exposure apparatus.

In accordance with the present invention, since the substrate movingdevice that is movable while holding the substrate is provided above theprojection optical system, a liquid immersion region can be formedbetween the projection optical system and the substrate, with the liquidbeing held on the upper end portion of the projection optical systemfixed at a predetermined position. That is, since it is configured suchthat the substrate moves relative to the liquid, scattering of theliquid can be suppressed, and deterioration of the pattern imageprojected onto the substrate can be prevented. In addition, sincepipings and the like for supplying and recovering the liquid for formingthe liquid immersion region on the upper end portion of the fixedprojection optical system need not be connected to the substrate movingdevice (substrate stage), deterioration of the movement accuracy of thesubstrate stage due to the pipings and the like does not occur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an outline configuration drawing showing a first embodiment ofan exposure apparatus of the present invention.

FIG. 2 is an enlarged drawing of a main part of FIG. 1 and is asectional side view showing a liquid immersion unit and its vicinity.

FIG. 3 is a plan view of the liquid immersion unit of FIG. 2 viewed fromabove.

FIG. 4 is a plan view showing another liquid immersion unit embodiment.

FIG. 5 is an enlarged main part drawing showing a second embodiment ofan exposure apparatus of the present invention.

FIG. 6 is a plan view of the liquid immersion unit of FIG. 1 viewed fromabove.

FIG. 7 is a plan view showing another liquid immersion unit embodiment.

FIG. 8 is a flowchart showing an example of a semiconductor devicemanufacturing process.

DETAILED DESCRIPTION OF THE INVENTION

Now, referring to the drawings, an exposure apparatus of the presentinvention will be described. FIG. 1 is an outline configuration drawingshowing a first embodiment of an exposure apparatus of the presentinvention.

Referring to FIG. 1, an exposure apparatus EX is provided with a maskstage MST that holds a mask M, a substrate stage PST that holds asubstrate P, an illumination optical system IL that illuminates the maskM held by the mask stage MST with exposure light EL, a projectionoptical system PL that projects a pattern image of the mask Milluminated with the exposure light EL onto the substrate P held by thesubstrate stage PST, and a controller CONT that controls the overalloperation of the exposure apparatus EX. The projection optical system PLis configured to form an image plane thereabove. The mask stage MST thatholds the mask M is disposed under the projection optical system PL, andon the other hand, the substrate stage PST that holds the substrate P isdisposed above the projection optical system PL.

The exposure apparatus EX of the embodiment is a liquid immersion typeexposure apparatus to which a liquid immersion method is applied, withthe exposure wavelength being shortened in effect, to improve theresolution and at the same time to widen the depth of focus and isprovided with a liquid immersion unit 100 constituting a part of aliquid immersion device that fills at least a portion of the spacebetween the projection optical system PL and the substrate P. The liquidimmersion unit 100 is provided with a liquid bath 10 that is fixed tothe upper end portion on the image plane side of projection opticalsystem PL, a liquid supply device 1 that supplies liquid 30 via a supplypipe 3 forming a flow path to the liquid bath 10, and a liquid recoverydevice 2 that recovers the liquid via a recovery pipe 4 forming a flowpath of the liquid from the liquid bath 10. And, in the exposureapparatus EX, at least while transferring the pattern image of the maskM onto the substrate P, at least a portion of the space between theprojection optical system PL and the substrate P is filled with theliquid 30 supplied from the liquid supply device 1 of the liquidimmersion unit 100 and a liquid immersion region AR2 is formed so as toinclude the projection area AR1 of the projection optical system PL.Specifically, in the exposure apparatus EX, the space between theoptical element PLa located at the upper end portion of the projectionoptical system PL and the exposure surface (top surface) of thesubstrate P is filled with the liquid 30, and the pattern image of themask M is projected onto the substrate P via the projection opticalsystem PL and the liquid 30 between the projection optical system PL andthe substrate P, and thus the substrate P is exposed.

The embodiment will now be explained as exemplified by a case of the useof the scanning type exposure apparatus (so-called scanning stepper) asthe exposure apparatus EX in which the substrate P is exposed with thepattern formed on the mask M while synchronously moving the mask M andthe substrate P in mutually different directions (opposite directions)along the scanning direction. In the following description, it isassumed that the direction that coincides with the optical axis AX ofthe projection optical system PL is referred to as the Z-axis direction,that the synchronous movement direction (the scanning direction), in aplane perpendicular to the Z-axis direction, of the mask M and thesubstrate P is referred to as the X-axis direction, and that thedirection perpendicular to the Z-direction and to the Y-direction isreferred to as the Y-direction (the non-scanning direction). Further, itis assumed that the direction around the X-axis, the direction aroundthe Y-axis, and the direction around the Z-axis are respectivelyreferred to as the θX-direction, the θY-direction, and the θZ-direction.It should be noted that the “substrate” referred to herein includes asemiconductor wafer over which a photoresist, a photosensitive material,is coated and that the “mask” includes a reticle formed with a devicepattern to be reduction projected onto a substrate.

The illumination optical system IL is for illuminating the mask M heldby the mask stage MST with the exposure light EL and comprises anexposure light source, an optical integrator for uniforming theilluminance of a light flux emitted from the exposure light source, acondenser lens for condensing the exposure light EL from the opticalintegrator, a relay lens system, a variable field stop for setting anillumination area on the mask M formed by the exposure light EL to be ofa slit-like shape, etc. A predetermined illumination area on the mask Mis illuminated, by the illumination optical system IL, with the exposurelight EL having a uniform illuminance distribution. As the exposurelight EL emitted from the illumination optical system IL, for example, abright line of ultraviolet region (g-line, h-line, i-line) emitted froma mercury lamp, a deep ultraviolet light (DUV light) such as a KrFexcimer laser light (wavelength of 248 nm), and a vacuum ultravioletlight (VUV light) such as an ArF excimer laser light (wavelength of 193nm) or an F₂ laser light (wavelength of 157 nm) may be used. In theembodiment, an ArF excimer laser light is used.

The mask stage MST is for supporting the mask M, is disposed under theprojection optical system PL, and is two-dimensionally movable andfinely rotatable in the θZ-direction, in a plane perpendicular to theoptical axis AX, i.e., in the XY-plane. In the mask stage MST areprovided vacuum suction holes for vacuum sucking mask M. The mask M issucked by and held on the mask stage MST via the vacuum suction holes sothat the pattern surface of the mask M is directed upwardly (in the +Zdirection). Further, the mask MST is driven by mask stage driving unitMSTD such as a linear motor. The mask stage driving unit MSTD iscontrolled by the controller CONT. The mask stage MST is provided with amoving mirror 50. Further, a laser interferometer 51 is positioned at aposition facing the moving mirror 50. The two-dimensional position andthe rotation angle of the mask M held by the mask stage MST are measuredby the laser interferometer 51 in real time, and the measurement resultsare outputted to the controller CONT. By driving the mask stage drivingunit MSTD based on the measurement results from the laser interferometer51, the controller CONT performs positioning of the mask M held by themask stage MST.

The projection optical system PL is for projection exposing the patternof the mask M onto the substrate P at a predetermined projectionmagnification of β. The projection optical system PL is constituted by aplurality of optical elements, including an optical element (lens) PLadisposed at the substrate P side upper end portion, and those opticalelements are supported by a lens barrel PK. And, the projection opticalsystem PL is arranged such that it forms thereabove an image plane. Inthe embodiment, the projection optical system PL is a reduction systemof which projection magnification β is, e.g., ¼ or ⅕. It should be notedthat the projection optical system PL may also be either a 1×magnification system or a magnifying system. Also note that the opticalelement PLa at the upper end portion of the projection optical system PLof the embodiment is detachable (exchangeable) relative to the lensbarrel PK, and the liquid 30 of the liquid immersion region AR2 is incontact with the optical element PLa. The liquid contact surface of theoptical element PLa is a plane substantially parallel to the XY-plane.

The substrate stage PST constituting a part of a substrate moving deviceis movable while holding substrate P. The substrate stage PST isprovided with a Z stage 52 that holds substrate P via a substrateholder, a XY stage 53 that supports the Z stage 52, and a base 54 thatsupports the XY stage 53. The base 54 is supported by a supportingmember different from a supporting member that supports, e.g., theprojection optical system PL. The substrate holder of the substratestage PST holds the substrate P so that the substrate P's exposuresurface that is coated with a photosensitive material and is to beexposed is directed downwardly (in the −Z direction). On the surface(under surface) of the substrate holder are provided a plurality ofvacuum suction holes that communicate with a vacuum device. Thesubstrate holder sucks and holds the substrate P via the vacuum suctionholes. Further, the substrate stage PST is driven by the substrate stagedriving unit PSTD such as a linear motor. The substrate stage drivingunit PSTD is controlled by the controller CONT. By driving the Z stage52, the Z-direction position (focus position) and the θX-direction andθY-direction positions of the substrate P held by the Z stage 52 arecontrolled. Further, by driving the XY stage 53, the XY-directionposition (the position in the direction substantially parallel to theimage plane of the projection optical system PL) of the substrate P iscontrolled. More specifically, the Z stage 52, by controlling the focusposition and inclination angle of the substrate P, makes the surface ofthe substrate P to coincide with the image plane of the projectionoptical system PL in an auto-focus manner and an auto-leveling manner,the XY stage 53 performs positioning of the substrate P in the X-axisand Y-axis directions. It is to be noted that needless to say, the Zstage and the XY stage may be integrally constructed.

The substrate stage PST (Z stage 52) is provided with a moving mirror55. Further, a laser interferometer 56 is positioned at a positionfacing the moving mirror 55. The two-dimensional position and therotation angle of the substrate P held by the substrate stage PST aremeasured by the laser interferometer 56 in real time, and themeasurement results are outputted to the controller CONT. By driving thesubstrate stage driving unit PSTD based on the measurement results fromthe laser interferometer 56, the controller CONT performs positioning ofthe substrate P held by the substrate stage PST.

FIG. 2 is an enlarged drawing of a main part of FIG. 1 and is asectional side view showing the liquid immersion unit 100. In FIG. 2,the liquid immersion unit 100 is provided with the liquid bath 10 thathas a side wall portion 10C and can hold the liquid 30, the liquidsupply device 1 that supplies the liquid 30 to the liquid bath 10 viathe supply pipe 3, and the liquid recovery device 2 that recovers theliquid 30 via the recovery pipe 4.

The liquid supply device 1 is provided with a tank that stores theliquid 30, a compressing pump, etc. and supplies the liquid 30 to theliquid bath 10 via the supply pipe 3. The liquid supply operation of theliquid supply device 1 is controlled by the controller CONT. Thecontroller CONT can control the per-unit-time liquid supply amount tothe liquid bath 10 of the liquid supply device 1. Further, the liquidsupply device 1 is provided with a temperature adjusting device thatadjusts the temperature of the liquid 30 to be supplied to the liquidbath 10. By using the temperature adjusting device, the liquid supplydevice 1 sets the temperature of the liquid 30 to be supplied to theliquid bath 10 to be, for example, substantially the same temperature asthat inside a chamber in which the exposure apparatus EX isaccommodated. Further, the supply pipe 3 is provided with a rectifyingmembers 5 for rectifying the liquid 30 to be supplied to the liquid bath10. The rectifying members 5 are constituted by, e.g., a porous materialor a slit member having a slit-shaped flow path. Still further, theliquid supply device 1 may be provided with a gas bubble removal device(a degas unit) that removes gas bubbles contained in the liquid 30 to besupplied to the liquid bath 10. The gas bubble removal device can beconstructed by, for example, a heating device that removes the gasbubbles by heating the liquid 30 or a decompressing unit in which theliquid 30 is stored in a predetermined a container and, by reducing thepressure inside the container, the gas bubbles are removed.

In the embodiment, purified water is used as the liquid 30. The purifiedwater can transmit not only ArF excimer laser light, but also theexposure light EL even when it is, for example, a bright line ofultraviolet region (g-line, h-line, or i-line) emitted from a mercurylamp or deep ultraviolet light (DUV light) such as KrF excimer laserlight (wavelength of 248 nm).

The liquid recovery device 2 is for recovering the liquid 30 in theliquid bath 10, is provided with, e.g., a suction device such as avacuum pump, a tank that stores the recovered liquid 30, etc. The liquidrecovery device 2 recovers the liquid 30 in the liquid bath 10 via therecovery pipe 4. The liquid recovery operation of the liquid recoverydevice 2 is controlled by the controller CONT, and the controller CONTcan control the per-unit-time liquid recovery amount of the liquidrecovery device 2.

The liquid bath 10 is for holding the liquid 30. The liquid bath 10 hasthe side wall portion 10 c, and is attached to the upper end portion ofthe lens barrel of the projection optical system PL. On the top portionof the liquid bath 10 is formed an opening portion 10A, and the liquid30 held by the liquid bath 10 is exposed toward the outside of theliquid bath 10 via the opening portion 10A. Here, the size of theopening portion 10A is formed to be larger than that of the projectionarea AR1 of the projection optical system PL. On the other hand, in abottom portion 10D of the liquid bath 10 is formed a through-hole 10B.Into the through-hole 10B of the liquid bath 10 is fitted the lensbarrel upper portion (not shown) of the projection optical system PL,and between the through-hole 10B and the lens barrel is provided asealing member for preventing leakage of the liquid 30 in the liquidbath 10. Further, the upper end surface of the optical element PLa ofthe projection optical system PL is positioned to be lower than theupper end surface of the side wall portion 10 c of the liquid bath 10;and thus, it is configured such that when the liquid bath 10 is filledwith liquid 30, the upper end portion including the upper end surface ofthe optical element PLa is immersed in the liquid 30. Here, the liquidbath 10 is formed by, e.g., a ceramic material. Such a ceramic material,even if a part thereof elutes into the liquid 30, hardly affects thephotosensitive material coated on the exposure surface of the substrateP.

The substrate stage PST is configured such that the exposure surface ofthe substrate P held by the stage is located apart from the upper endportion of the liquid bath 10 by a predetermined distance. Morespecifically, the distance between the substrate P and the liquid bath10 is set such that the exposure surface of the substrate P and theliquid 30 exposed upwardly from the opening portion 10A of the liquidbath 10 come into contact with each other through the surface tension ofthe liquid 30.

FIG. 3 is a view of the liquid immersion unit 100 viewed from above. InFIG. 3, the upper end optical element PLa of the projection opticalsystem PL is formed to be circular when viewed from the top, and theliquid bath 10 and its opening portion 10A are also formed to becircular when viewed from the top. And, the optical element PLa islocated in substantially the center portion of the liquid bath 10 (theopening portion 10A). The supply pipe 3 connected to the liquid supplydevice 1 branches, halfway, into three flow paths, and each of thebranch flow paths is respectively connected to either one of the threesupply ports 6A-6C provided on the −X side of the optical element PLa ofthe projection optical system PL. On the other hand, on the +X side ofthe optical element PLa are provided two recovery ports 7A and 7B; andthe flow paths, each connected to either one of those recovery ports 7Aand 7B, are assembled into one, and the assembled flow path is connectedto the recovery pipe 4. In other words, it is configured such that thesupply ports 6A-6C connected to the liquid supply device 1 via thesupply pipe 3 are provided on the −X side, and the recovery ports 7A and7B connected to the liquid recovery device 2 via the recovery pipe 4 areprovided on the +X side, in a manner in which the upper end portion ofthe optical element PLa of the projection optical system PL isinterposed between the supply ports and the recovery ports.

Further, supply ports 8A-8C and recovery ports 9A and 9B are disposed inthe arrangement in which the supply ports 6A-6C and the recovery ports7A and 7B are rotated by substantially 180 degrees. The supply ports8A-8C are connected to the liquid supply device 1 via the supply pipe11, and the recovery ports 9A and 9B are connected to the liquidrecovery device 2 via the recovery pipe 12. The supply ports 6A-6C andthe recovery ports 9A and 9B are disposed alternately in theY-direction, and the supply ports 8A-8C and the recovery ports 7A and 7Bare disposed alternately in the Y-direction.

And, in the case of performing scanning exposure by moving the substrateP in the scanning direction (+X direction) indicated by arrow Xa, thesupply and the recovery of the liquid 30 are performed by the liquidsupply device 1 and the liquid recovery device 2, by the use of thesupply pipe 3, the supply ports 6A-6C, the recovery pipe 4, and therecovery ports 7A and 7B. More specifically, when the substrate P movesin the +X direction, the liquid 30 is supplied from the liquid supplydevice 1 to the liquid bath 10 including the space between theprojection optical system PL and substrate P via the supply pipe 3 andthe supply ports 6A-6C, and, at the same time, the liquid 30 isrecovered by the liquid recovery device 2 via the recovery ports 7A and7B and the recovery pipe 4, with the liquid 30 flowing in the +Xdirection in liquid bath 10. On the other hand, in the case ofperforming scanning exposure by moving the substrate P in the scanningdirection (−X direction) indicated by arrow Xb, the supply and therecovery of the liquid 30 are performed by the liquid supply device 1and the liquid recovery device 2, by the use of the supply pipe 11, thesupply ports 8A-8C, the recovery pipe 12, and the recovery ports 9A and9B. More specifically, when the substrate P moves in the −X direction,the liquid 30 is supplied from the liquid supply device 1 to the liquidbath 10 including the space between the projection optical system PL andthe substrate P via the supply pipe 11 and the supply ports 8A-8C, and,at the same time, the liquid 30 is recovered by the liquid recoverydevice 2 via the recovery ports 9A and 9B and the recovery pipe 12, withthe liquid 30 flowing in the −X direction in the liquid bath 10.

In this way, the controller CONT, by using the liquid supply device 1and the liquid recovery device 2, makes liquid 30 flow along the movingdirection of the substrate P and in the same direction as the movingdirection of the substrate P. Thus, fresh and clean liquid 30 can becontinuously supplied to the space between the projection optical systemPL and the substrate P. And, by changing, in response to the scanningdirection, the direction in which liquid 30 is made to flow, the spacebetween the projection optical system PL and the substrate P can befilled with the liquid 30, both in of the case where the substrate P isscanned in the +X direction and in the case where the substrate P isscanned in the −X direction, which makes it possible to obtain a highresolution and a wide depth of focus.

By the way, on the side wall portion 10C or the bottom portion 10D ofthe liquid bath 10 may be attached, for example, a focus detectionsystem that can detect the surface position of the substrate P relativeto the image plane of the projection optical system PL. In this case,the focus detection light passes through the liquid 30.

Next, an explanation will be made about a procedure for exposing thesubstrate P with the pattern of the mask M by using the exposureapparatus EX described above.

Here, the exposure apparatus EX of the present embodimentprojection-exposes the pattern image of the mask M onto the substrate Pwhile moving mask M and substrate P in the X-direction (scanningdirection); and, during scanning exposure, a pattern image of a part ofthe mask M is projected onto the projection area AR1 formed above theprojection optical system PL, and in synchronization with the movementof the mask M in the −X direction (or in the +X direction) at speed V,the substrate P moves, via the XY stage 53, in the +X direction (or inthe −X direction) at speed β·V (β is the projection magnification). And,after completion of exposure for one shot area, a next shot area isbrought to the projection area through the stepping movement of thesubstrate P, and in this way, exposure for each shot area issuccessively performed through the step-and-scan method.

First, after the mask M being loaded on the mask stage MST and at thesame time the substrate P being loaded on the substrate stage PST, thecontroller CONT drives the liquid supply device 1 and the liquidrecovery device 2 and starts the supply and recovery operations of theliquid 30 relative to the liquid bath 10. Liquid 30 delivered from theliquid supply device 1 to form the liquid immersion region AR2, afterflowing through the supply pipe 3, is supplied to the liquid bath 10 viathe supply ports 6A-6C. And, the controller CONT illuminates the mask Mwith the exposure light EL by means of the illumination optical systemIL while synchronously moving the mask M and the substrate P andprojects the pattern image of the mask M onto the substrate P via theprojection optical system PL and the liquid 30.

While performing scanning exposure with the substrate P being moved in,e.g., the +X-direction, the liquid supply device 1 and the liquidrecovery device 2 continue to perform the liquid supply operation andthe liquid recovery operation. Since, by doing so, thetemperature-adjusted liquid 30 is always supplied from the liquid supplydevice 1 to the liquid bath 10, excessive temperature change(temperature rise) of the liquid 30 in liquid bath 10 due to theirradiation heat of the exposure light can be suppressed, which realizesa high accuracy exposure of the pattern image.

With the liquid supply operation by the liquid supply device 1 and theliquid recovery operation by the liquid recovery device 2 beingperformed in a coordinated manner, the liquid 30 flows, between thesubstrate P and the optical element PLa of the projection optical systemPL, in the direction parallel to (in the same direction as) the scanningdirection of the substrate P. Further, when the liquid supply operationby the liquid supply device 1 and the liquid recovery operation by theliquid recovery device 2 are performed in a coordinated manner, theexposure surface of the substrate P and the surface of liquid 30 exposedupwardly from the aperture portion 10A of the liquid bath 10 come intocontact with each other with the aid of the surface tension of liquid30, and thus the liquid 30 is disposed between the projection area AR1on the substrate P and the optical element PLa, forming the liquidimmersion region AR2. Thus, the substrate P is exposed in the state inwhich the substrate P is held by the substrate stage PST such that theexposure surface of the substrate P comes into contact with the surfaceof liquid 30. In this configuration, since the exposure surface of thesubstrate P and the surface of liquid 30 are in contact with each otherwith the aid of the surface tension of liquid 30, a slight gap is formedbetween the exposure surface of the substrate P and the upper endsurface of the liquid bath 10. Because of this, the substrate stage PSTcan freely move the substrate P in the XY-plane, with the substrate notbeing in contact with liquid bath 10.

By the way, when the scanning speed of the substrate P is changed, thecontroller CONT may change, depending on the scanning speed of thesubstrate P, the per-unit-time liquid supply amount of the liquid supplydevice 1 and the per-unit-time liquid recovery amount of the liquidrecovery device 2. Specifically, when the moving speed of the substrateP is increased, the per-unit-time liquid supply amount and theper-unit-time liquid recovery amount are increased. By doing so, theflow rate of liquid 30 flowing between the projection optical system PLand the substrate P also increases in accordance with the moving speedof the substrate P, and thus the liquid immersion region AR2 can besmoothly formed between the projection optical system PL and thesubstrate P. In addition, it is preferable that the size of the liquidbath 10 (the aperture portion 10A) is determined in accordance with themoving speed of the substrate P. More specifically, when the movingspeed of the substrate P is made to be higher, there arises thepossibility that the liquid 30 in the liquid bath 10 is dragged bysubstrate P, the formation of the liquid immersion region AR2 becomesunstable, and the liquid 30 cannot be disposed on the projection areaAR1 on the substrate P, though the liquid 30 can be, by making theliquid bath 10 larger to make the area of the contact surface betweenthe substrate P and the liquid 30 larger, smoothly disposed on theprojection area AR1, even if the moving speed of the substrate P is madeto be higher.

Further, the distance between the liquid bath 10 and the substrate Pheld by substrate stage PST may be determined in accordance with thesurface tension (interfacial tension) of the liquid 30 to be used.Purified water is used as liquid 30 in the embodiment; but, when anotherkind of liquid is used, since the surface tension values (interfacialtension values) of liquids vary depending on their materialcharacteristics, the distance between the liquid bath 10 and thesubstrate P is set in accordance with the surface tension of the liquidused.

As described above, since the image plane of the projection opticalsystem PL is formed above the projection optical system PL, and, at thesame time, the substrate stage PST that is movable while holding thesubstrate P above the projection optical system PL is provided, theliquid bath 10 of the liquid immersion unit 100 can be provided on theupper end portion of the projection optical system PL that does notmove, and the liquid immersion region AR2 can be formed between theprojection optical system PL and the substrate P. Since the position ofthe liquid bath 10 is fixed, the undulation of the liquid surfaceexposed upwardly from the aperture portion 10A of the liquid bath 10 andthe scattering of the liquid can be prevented, and the deterioration ofthe pattern image projected onto the substrate P can be suppressed.Further, since, with the liquid bath 10 being provided on the upper endportion of the projection optical system PL, the liquid supply device 1for supplying liquid 30 to form the liquid immersion region AR2 and thesupply pipe 3 connected thereto, and the liquid recovery device 2 forrecovering liquid 30 and the recovery pipe 4 connected thereto need notbe attached to the substrate stage PST which is a moving portion, thedisadvantage, due to the device and the pipes, that the movement of thesubstrate stage PST is disturbed can be suppressed, for example.

It should be noted that although, in the embodiment, it is configuredsuch that the temperature of liquid 30 supplied to the liquid bath 10 toform the liquid immersion region AR2 is adjusted by the temperatureadjusting device provided to the liquid supply device 1, it may also beconfigured such that a temperature adjusting device of liquid 30 forforming the liquid immersion region AR2 is attached to the liquid bath10.

It is to be noted that although, in the embodiment, it is configuredsuch that during the scanning exposure, the liquid supply operation andthe liquid recovery operation are continued to continuously make liquid30 flow, the liquid immersion exposure can also be performed in thestate that the liquid 30 is, without being made to flow, pooled in theliquid bath 10. However, with the supply and recovery of liquid 30 beingperformed, occurrence of temperature change (temperature rise) of liquid30 in the liquid bath 10 due to the exposure light irradiation heat canbe suppressed, and deterioration of the pattern can be prevented.Further, with the supply and recovery of liquid 30 being continuouslyperformed during the exposure, clean liquid 30 can be always suppliedfrom the liquid supply device 1 to the liquid bath 10, and, at the sametime, even if impurities have come to be mixed in the liquid 30 of theliquid bath 10, the impurities can be immediately recovered from theliquid bath 10 by the liquid recovery device 2.

It should be further noted that as shown in FIG. 4, on each of theY-direction side portions between which the optical element PLa of theprojection optical system PL is interposed may be provided supplynozzles 13A-13C, supply nozzles 14A-14C, recovery nozzles 15A, 15B, 16A,and 16B. By virtue of those supply nozzles and recovery nozzles, evenwhen the substrate P moves in the non-scanning direction (the Y-axisdirection) during its stepping movement, the liquid 30 can be stablysupplied between the projection optical system PL and the substrate P.Still further, while, in the above-described embodiment, the liquid bath10 is attached to the lens barrel in the vicinity of the upper endportion of the projection optical system PL, it may also be configuredsuch that the bath is held by a supporting member separated from theprojection optical system PL.

Next, referring to FIGS. 5 and 6, a second embodiment exposure apparatusof the present invention will be described. FIG. 5 is a sectional sideview of liquid immersion unit 100 of the second embodiment; FIG. 6 is aplan view thereof viewed from above. Here, in the following description,the same or equivalent constituent elements as those in theabove-described embodiment are denoted by the same reference numerals,and their descriptions will be abridged or omitted.

In FIGS. 5 and 6, the liquid immersion unit 100 is provided with aliquid immersion forming member 20 that is attached to the upper endportion optical element PLa of the projection optical system PL and hasan upper surface 21 facing the substrate P, with liquid supply ports23A-23C that formed on the upper surface 21 and are connected to theliquid supply device 1 via flow paths 22A-22C formed inside the formingmember 20 and supply pipe 3, and with liquid recovery ports 25A and 25Bthat formed on the upper surface 21 and are connected to the liquidrecovery device 2 via flow paths 24A and 24B and recovery pipe 4. Theforming member 20 has, in its center portion, as viewed from the top, ahole portion 20A that fits with the optical element PLa of theprojection optical system PL, and it is configured such that when theoptical element PLa is fitted with the hole portion 20A, the uppersurface 21 of the forming member 20 and the upper end surface of theoptical element PLa of the projection optical system PL aresubstantially flush with each other. Each of the liquid supply ports23A-23C is provided on the −X side of the optical element PLa of theprojection optical system PL and discharges the liquid 30 upwardly. Onthe other hand, the liquid recovery ports 25A and 25B are provided onthe +X side of the optical element PLa and suck the liquid 30downwardly. It should be noted that while, in this embodiment, threeliquid supply ports and two liquid recovery ports are provided with, thenumber and arrangement thereof may be set in a discretionary way.Further, as well as the first embodiment, separate liquid supply portsand liquid recovery ports may be provided on the upper surface 21 in thearrangement in which the above-described liquid supply ports 23A-23C andliquid recovery ports 25A and 25B are rotated by substantially 180degrees.

Outside of the liquid supply ports 23A-23C and the liquid recovery ports25A and 25B on the upper surface 21 are provided trap portions 28 and 29that recover liquid 30 that has not been recovered by the liquidrecovery ports. Each of the trap portions 28 and 29 is an arc-shapedgroove, as viewed from the top, and is provided in the position suchthat the optical element PLa of the projection optical system PL isinterposed between the trap portions.

In FIG. 5, a flow path 30 connected to the trap portion 29 is connectedto a tank 32 and to a vacuum pump 34 as a suction device, via a conduit31 provided outside the forming member 20. The flow path that connectsthe tank 32 with the vacuum pump 34 is provided with a valve 33. Thetank 32 is provided with a discharge flow path 32A, and it is configuredsuch that when the liquid 30 has pooled in the tank up to apredetermined amount, the liquid is discharged through the dischargeflow path 32A. It should be noted that although not shown, a flow path35 connected to the trap portion 28 is also connected to a tank, avalve, and a vacuum pump, similar to the above-described ones.

When the substrate P is scan-exposed while moving the substrate in the+X direction, the controller CONT drives the liquid supply device 1 andthe liquid recovery device 2, supplies the liquid 30 to the uppersurface 21 via the liquid supply ports 23A-23C, and forms the liquidimmersion region AR2 between the optical element PLa of the projectionoptical system PL and the substrate P. And, the liquid 30 is recoveredvia the liquid recovery ports 25A and 25B, and the substrate P isexposed, with liquid 30 being made to flow in the direction parallel to(in the same direction as) the scanning direction of the substrate P. Inthis case, the liquid 30 supplied from, e.g., the liquid supply device 1via supply ports 23A-23C flows in the manner that the liquid, beinginduced by the +X direction movement of the substrate P, is pulled intothe space between the projection optical system PL and the substrate P,and thus, even if the supply energy of the liquid supply device 1 issmall, the temperature-adjusted liquid 30 is always supplied from theliquid supply device 1 between the upper end surface of the opticalelement PLa and the substrate P, and excessive temperature change(temperature rise) of the liquid 30 due to the irradiation heat of theexposure light is suppressed, which realizes a high accuracy exposure ofthe pattern image.

The liquid bath having the side wall is used to hold the liquid 30 inthe first embodiment; in contrast, it is configured in the secondembodiment such that the liquid 30 is disposed between the planar uppersurface 21 and the upper end surface of the optical element PLa, and thesubstrate P, and thus, even when the substrate P is inclined by a largeamount, the substrate P does not come into contact with the formingmember 20. And, since, also in this embodiment, it is configured suchthat the substrate P is moved in the state that the liquid immersionforming member 20 of the liquid immersion unit 100 is fixed to theprojection optical system PL that does not move, undulation, scattering,etc. of the liquid 30 do not occur, which realizes stable projection ofthe pattern image onto the substrate P.

It should be noted that while, in the embodiment, it is configured suchthat the supply and recovery operations of the liquid 30 are performedthrough the multiple liquid supply ports and liquid recovery portsprovided in the predetermined positions on the upper surface 21, it mayalso be configured such that by combining the multiple liquid supplyports and liquid recovery ports respectively, for example, as shown inFIG. 7, a liquid supply hole 23 and a liquid recovery hole 25, each longhole-shaped (arc-shaped) as viewed from the top, are provided. Further,as shown in FIG. 7, the trap portion 28 may be formed annularly so as tosurround the optical element PLa of the projection optical system PL.Still further, it may be configured such that, without providing theliquid recovery ports 25A and 25B, all of the supplied liquid 30 isrecovered by the trap portions 28 and 29.

It is to be noted that in the embodiment, the trap portions forrecovering the liquid 30 that has not been recovered by the liquidrecovery ports are constituted by the grooves and the vacuum pumps(suction devices) connected thereto, but, by, for example, disposingporous members, such as sponges, in the grooves, the liquid 30 that hasnot been recovered can be recovered and held by the porous members.

As described above, the liquid 30 of the embodiments is constituted bypurified water. Purified water has the advantage that it can be easilyavailable in large quantities in, e.g., a semiconductor manufacturingfactories and also the advantage that it does not adversely affectphotoresist on the substrate P, the optical elements (lenses), etc.Further, purified water does not adversely affect the environment andcontains scarcely any impurities. Thus, the effect that it cleans thesurface of the substrate P and the surface of the optical elementprovided at the end portion of the projection optical system PL can beexpected. And, the refractive index n of purified water (water) relativeto the exposure light EL having a wavelength of about 193 nm isapproximately 1.44, and when ArF excimer laser light (having 193 nmwavelength) is used as the light source of exposure light EL, thewavelength is effectively shortened, on the substrate P, as multipliedby 1/n, i.e., effectively becomes approximately 134 nm, and thus, a highresolution can be obtained. Furthermore, because the depth of focus willincrease approximately n times, i.e., approximately 1.44 times, that ofin air, the numerical aperture of the projection optical system PL canbe further increased if it is preferable to ensure a depth of focusapproximately the same as that when used in air, and the resolution isalso improved from this standpoint.

It should be noted that if the pressure, caused by the flow of theliquid 30, of the space between the optical element located at the endof the projection optical system PL and the substrate P is high, it maybe configured such that the optical element is rigidly fixed so as notto move due to the pressure, instead of making the optical elementexchangeable.

It should be noted that while, in the embodiments, the liquid 30 iswater, the liquid 30 may be a liquid other than water. For example, whenthe light source of the exposure light EL is an F₂ laser, the F₂ laserlight does not transmit through water, and thus, as the liquid 30, afluorofluid that can transmit the F₂ laser light may be used. Further,as the liquid 30, a material (e.g., cedar oil) that can transmit theexposure light EL, has a high refractive index as high as practicable,and does not affect the projection optical system and the photoresistapplied to the surface of the substrate P can also be used.

It is to noted that the substrate P of each of the above-describedembodiments, can be not only a semiconductor wafer for manufacturing asemiconductor device, but also a glass substrate for a display device, aceramic wafer for a thin film magnetic head, a master mask or reticle(synthetic quartz or silicon wafer), etc.

As the exposure apparatus EX, in addition to a scan type exposureapparatus (scanning stepper) in which while synchronously moving themask M and the substrate P, the pattern of the mask M is scan-exposed, astep-and-repeat type projection exposure apparatus (stepper) thatexposes the full pattern of the mask M in the state in which the mask Mand substrate P are stationary, and the substrate P is successivelymoved stepwise can be used. Also, the present invention can be appliedto a step-and-stitch type exposure apparatus in which at least twopatterns are transferred onto the substrate P in a partially overlappingmanner.

Also, the present invention can be applied to a twin stage type exposureapparatus, which is disclosed in, e.g., Japanese Unexamined PatentApplication, First Publication Nos. H10-163099 and H10-214783, andPublished Japanese Translation No. 2000-505958 of the PCT InternationalPublication.

The type of exposure apparatus EX, the present invention is not limitedto an exposure apparatus, which exposes a semiconductor pattern onto thesubstrate P, for manufacturing semiconductor devices, but can also beapplied to a variety of exposure apparatuses, e.g., an exposureapparatus for manufacturing liquid crystal display devices or adisplays, an exposure apparatus for manufacturing thin film magneticheads, an exposure apparatus for manufacturing image pickup devices, andan exposure apparatus for manufacturing reticles or masks.

When using a linear motor (see U.S. Pat. No. 5,623,853 or U.S. Pat. No.5,528,118) in substrate stage PST or mask stage MST, either air-cushiontype linear motor using an air bearing or a magnetic levitation typelinear motor using a Lorentz force or reactance force may be used.Further, each of substrate stage PST and mask stage MST may be either ofa type moving along a guide or of a guideless type having no guide.

For the driving mechanism for each of the substrate stage PST and themask stage MST, a planar motor may be used that opposes a magnet unit inwhich magnets are two-dimensionally arranged to an armature unit inwhich coils are two-dimensionally arranged, and that drives each of thesubstrate stage PST and the mask stage MST by an electromagnetic force.In this case, either one of the magnet unit and the armature unit isattached to the stage PST or the stage MST, and the other unit isattached to the moving surface side of the stage PST or the stage MST.

A reaction force generated by the movement of the substrate stage PSTmay be, as described in Japanese Unexamined Patent Application, FirstPublication No. H08-166475 (U.S. Pat. No. 5,528,118), mechanicallyreleased to the floor (earth) by use of a frame member so that the forcedoes not transmit to the projection optical system PL.

A reaction force generated by the movement of the mask stage MST may be,as described in Japanese Unexamined Patent Application, FirstPublication No. H08-330224 (U.S. patent application Ser. No.08/416,558), mechanically released to the floor (earth) by use of aframe member so that the force does not transmit to the projectionoptical system PL.

As described above, the exposure apparatus EX according to theembodiments of the present application is built by assembling varioussubsystems, including each element listed in the claims of the presentapplication, in such a manner that prescribed mechanical accuracy,electrical accuracy, and optical accuracy are maintained. In order toensure the various accuracies, prior to and after the assembly, everyoptical system is adjusted to achieve its optical accuracy, everymechanical system is adjusted to achieve its mechanical accuracy, andevery electrical system is adjusted to achieve its electrical accuracy.The process of assembling each subsystem into the exposure apparatusincludes mechanical interfaces, electrical circuit wiring connections,and air pressure plumbing connections between each subsystem. Needlessto say, there is also a process where each subsystem is assembled priorto the assembling of the exposure apparatus from the various subsystems.On completion of the process of assembling the various subsystems in theexposure apparatus, overall adjustment is performed to make sure thatevery accuracy is maintained in the complete exposure apparatus.Additionally, it is desirable to manufacture the exposure apparatus in aclean room, in which the temperature, purity, etc. are controlled.

As shown in FIG. 8, micro devices such as semiconductor devices aremanufactured by a series of steps, including: step 201 in which themicro device's function and performance design is performed; step 202 inwhich a mask (reticle) is manufactured based on the design step; step203 in which a substrate, the device's base material, is manufactured;step 204 in which the mask pattern is exposed onto the substrate by theexposure apparatus EX according to the above-described embodiments;device assembly step 205 (including the dicing process, bonding process,and packaging process); inspection step 206.

In accordance with the present invention, since scattering of a liquidfor forming a liquid immersion region can be suppressed, and, at thesame time, the movement of a substrate stage is not obstructed bypipings and the like for supplying and recovering the liquid, requiredpatterns can be exposed onto the substrate with high accuracy.

1. A liquid immersion photolithography system comprising: an opticalsystem that images electromagnetic radiation upwards onto a substrate;and a liquid between the optical system and the substrate.
 2. The liquidimmersion photolithography system of claim 1, wherein the liquid forms ameniscus above the optical system.
 3. The liquid immersionphotolithography system of claim 1, wherein the liquid forms afountainhead above the optical system.
 4. The liquid immersionphotolithography system of claim 1, wherein the optical system includesa housing with at least one catch basin positioned to capture strayliquid.
 5. The liquid immersion photolithography system of claim 1,wherein the optical system includes: a housing in which a plurality oflenses are mounted, the housing including a pressure region between anuppermost lens of the plurality of lenses and a top of the housing; anopening in the top of the housing; and a liquid seal between anuppermost lens of the plurality of lenses and the pressure region. 6.The liquid immersion photolithography system of claim 5, wherein adistance between the substrate and the top of the housing isapproximately 50-150 microns.
 7. The liquid immersion photolithographysystem of claim 5, wherein a distance between the substrate and the topof the housing is between 50 microns and 500 microns.
 8. The liquidimmersion photolithography system of claim 5, wherein the top of thehousing has a hydrophobic surface.
 9. A liquid immersionphotolithography system comprising: an optical system adapted forexposure of a lower surface of a substrate; and a liquid that forms ameniscus between the optical system and the substrate.
 10. The liquidimmersion photolithography system of claim 9, wherein the projectionoptical system includes a housing with at least one catch basin adaptedto capture stray liquid.
 11. The liquid immersion photolithographysystem of claim 9, wherein the projection optical system includes: ahousing in which a plurality of lenses are mounted, the housingincluding a pressure region between an uppermost lens of the pluralityof lenses and a top of the housing; an opening in the top of thehousing; and a liquid seal between an uppermost lens of the plurality oflenses and the pressure region.
 12. The liquid immersionphotolithography system of claim 11, wherein the top of the housing hasa hydrophobic surface.
 13. The liquid immersion photolithography systemof claim 11, wherein the liquid is adapted to selectively be providedonly when wet exposure is needed.